Necrotizing Enterocolitis (NEC) –Causes, Treatment, and Prevention.

Overview

Necrotizing enterocolitis (NEC)
is an inflammation in the intestines (usually the colon) that can be
life-threatening if not treated right away. NEC may affect only the lining of
the intestine or its entire thickness. The damage caused by NEC to the
intestinal tissues can cause a hole in the intestines that allows the bacteria
normally present only in the intestinal tract to leak out into the abdomen and
cause infection. Once this occurs, the infection can progress very quickly and
is considered a medical emergency.

NEC most commonly affects
premature babies, accounting for 60 to 80% of cases. It is the most common
gastrointestinal emergency in the Neonatal Intensive Care Unit (NICU). It
usually occurs within 3-12 days after birth.

Pathophysiology

It is not really understood what
happens to cause necrotizing enterocolitis. The only risk factor identified is
prematurity. As we mentioned earlier, when a baby is born premature, they are
not born fully mature and developed. This may cause their gastrointestinal
system to move slower than normal. If the intestines aren’t digesting food
quickly enough, stool spends an increased time in the intestine and may
contribute to bacterial growth. NEC also seems to develop when the baby is
hypoxic, meaning their oxygen level in their blood is low, and they have
hypoperfusion, meaning they are not getting enough oxygen to the cells within
their body.

There are two factors which seem
to be at play in NEC- enteral feedings and bacteria.

Enteral Feedings and NEC

Premature infants often receive
enteral feedings, which consists of a tube that usually enters through their
nose and travels into their stomachs. Since they are premature, they are unable
to eat on their own, so formula is given through this tube to meet their
nutritional requirements.

When a premature baby receives
enteral feedings, it is believed to disrupt the integrity of the mucosa of the
intestine. Their blood flow and the motility of their intestine are decreased.
These factors cause the formula from their feedings to sit in the intestine
unabsorbed and provides a perfect environment for bacteria to proliferate.

Receiving feedings in this manner
when combined with bacteria proliferation injures the epithelial cells of the
intestine. This causes inflammation, which can lead to necrotizing.

The Role of Bacteria in NEC

Before a baby is born, the
intestine is a sterile environment. After they are born, bacteria will enter
the intestines and ideally help to develop a normal intestinal immune system.
Breastmilk helps in this development by helping to create a balanced flora of
bacteria in the intestine. But in NEC, bacteria growth is rampant and is
believed to be the toxic by-products induced by the food that is present in the
intestines. Evidence does show that using breastmilk instead of formula helps
to provide protection against the development of NEC.

What causes necrotizing enterocolitis (NEC)?

There is no single consistent
cause of necrotizing enterocolitis. In most cases, a specific cause isn’t
found. But experts believe these things might play a role:

An
underdeveloped (premature) intestine

Too
little oxygen or blood flow to the intestine at birth or later

Injury
to the intestinal lining

Heavy
growth of bacteria in the intestine that erodes the intestinal wall

Viral
or bacterial infection of the intestine

Formula
feeding (breastfed babies have a lower risk of NEC)

NEC sometimes seems to happen in
“clusters,” affecting several infants in the same nursery. This might
be coincidental, but some viruses and bacteria occasionally have been found in
babies with NEC. NEC does not spread from one baby to another, but a virus or
bacteria that cause it can. This is one reason all nurseries and NICUs have
very strict precautions to help prevent the spread of infection.

Risk factors of NEC

Fortunately, NEC is rare. It can
happen in any newborn baby, but it’s most common in premature babies who weigh
less than 3.25 lbs. Others who may be at risk include:

High-risk
or premature babies who are fed formula by mouth or tube

Those
who had a difficult delivery or have lowered oxygen levels

Infants
who have too many red blood cells in circulation

Babies
with existing gastrointestinal infections

Seriously
ill infants and those who’ve received a blood transfusion

What are the symptoms of NEC?

The symptoms of NEC often include
the following:

Swelling
or bloating of the abdomen

Discoloration
of the abdomen

Bloody
stool

Diarrhea

Poor
feeding

Vomiting

Your baby may also show symptoms
of an infection, such as:

Apnea,
or disrupted breathing

A
fever

Lethargy

Complications of necrotizing enterocolitis

Damage to the intestinal tissues
can lead to perforation (a hole) in the intestines. This allows the bacteria
normally present in the intestinal tract to leak out into the abdomen and cause
infection. The damage may only exist in a small area or it may progress to
large areas of the intestine. The disease can progress very quickly. Infection
in the intestines can be overwhelming to a baby and, even with treatment, there
may be serious complications. Problems from NEC may include the following:

Perforation
(hole) in the intestine

Scarring
or strictures (narrowing) of the intestine

Problems
with food absorption if large amounts of intestine must be removed

Severe,
overwhelming infection

Diagnosis and Test to detect NEC

A thorough physical examination
of the baby along with symptoms is carried out. The following investigations
are also done:

X-ray
of the baby’s belly.

Fecal
occult blood test is done to check for blood in the baby’s stool.

Tests
are done to look for bacteria in the blood, stool, urine or spinal fluid.

NEC diagnosis can be categorized
into three stages depending on the extent of the infection and the symptoms
displayed (5).

Stage
1 – Suspected NEC: The baby would display non-specific or general symptoms that
could indicate necrotizing enterocolitis. Symptoms include lethargy, fussiness,
and fever. An X-ray in this stage displays abdominal distention or gastric
residues but not the extent to prove it to be NEC.

Stage
2 – Proven NEC: X-rays show clear signs of NEC with the presence of large gas
globules within the intestine. Bowel sounds will be absent due to a
dysfunctional intestine.

Stage
3 – Advanced NEC: The intestine is damaged to the extent that there are holes
in the intestinal wall. The baby also has severe sleep apnea, low blood
pressure, and inflammation of the entire abdominal wall.

Treatment and Medications

Treatment
for Necrotizing Enterocolitis depends on the severity of the condition, the age
of the baby and the general health of the baby.

Necrotizing
enterocolitis treatment can last for a week to 10 days.

The
baby will be admitted to the hospital’s neonatal intensive care unit (NICU).

The
baby suffering from Necrotizing enterocolitis is fed intravenously. All oral
feedings are stopped.

Antibiotics
are given to fight with the infection associated with Necrotizing
enterocolitis.

A
tube is inserted through the nose to the stomach which removes excess fluids
and gas present in the intestine.

Surgery
for Necrotizing enterocolitis is done in severe cases where the baby is not
getting better or if perforation develops in the intestine.

Around
1 out of 4 babies having necrotizing enterocolitis need surgery.

Surgery
for Necrotizing Enterocolitis is done in two parts with these two procedures
being weeks or months apart.

The
first surgery for Necrotizing enterocolitis involves removing the damaged/dead
parts of the intestine and creating an ileostomy or a colostomy. This is done
so that the intestine can rest and heal.

In
ostomy, the stool exits the body via an opening in the belly and gets collected
in a bag.

The
second surgical treatment for Necrotizing enterocolitis is done to close the
ostomy site and allow the stool to pass normally through the body again.

After
the treatment for Necrotizing enterocolitis is complete, the baby will be
discharged if he/she is accepting feeds and not losing weight.

The
nurse from the hospital will instruct you on how to feed and care for the baby
at home.

Parents
of the baby tend to feel overwhelmed regarding the baby’s health. It is advised
to consult with a counselor or a social worker regarding your feelings and to
relieve stress.

How to Prevent Necrotizing Enterocolitis?

There is no precise prevention
for necrotizing enterocolitis since its cause is not apparent. However, you can
take precautions after consulting with the doctor if your baby falls into the
high-risk category. Here is what you can do to reduce the risk of NEC in your
baby:

Breast
milk:
Pediatric experts note that babies who have only breast milk are not so much at
risk of NEC Premature babies who are given food through tubes (enteral feeding)
should be given expressed milk to minimize NEC risk. Breast milk is also
beneficial for low birth weight infants. A study has found that providing low
birth-weight babies a feed consisting of at least 50% breast milk in the first
14 days after birth reduces the risk of NEC by six times (6).

Delaying
feed:
Feeding through the mouth can be delayed in the case of premature babies whose
gastrointestinal tract is still underdeveloped and immature. You can consider
it after doctor’s consultation. In any case, your infant would be in intensive
care at the hospital, which might delay oral feeding anyway.

Probiotics: Probiotic bacteria such as
Bifidus infantis and Lactobacillus acidophilus can help reduce the risk. But
there is limited research on their efficacy, the precise dosage, and the type
of bacteria that works. Consult your doctor before adopting this measure.